Intelligence, psychometrics, and the mind — explained from the evidence
Clear, referenced syntheses of the peer-reviewed literature — 142 articles written and reviewed by a doctoral-level editorial team.
Browse by topic
- IQ Scores & Ranges
Understanding IQ score classifications, percentile rankings, and what different score ranges mean for cognitive ability.
21 articles - IQ Testing & Measurement
Psychometric methods for measuring intelligence including test design, reliability, validity, and modern adaptive testing.
55 articles - Child Cognitive Development
How cognitive abilities develop from birth through adolescence, including environmental and genetic factors.
23 articles - Brain Health & Performance
Neuroscience of cognitive performance including exercise, diet, environmental factors, and neuroplasticity.
31 articles - Intelligence Theory & Models
Theoretical frameworks for understanding intelligence including CHC theory, fluid vs crystallized intelligence, and the g factor.
4 articles
All topics
- Child Cognitive Development3
- Cognitive Abilities and Intelligence21
- Cognitive Aging and Decline2
- Cognitive Development and Neurodevelopment16
- Cognitive Neuroscience and Brain Function18
- Educational Psychology and Interventions7
- Environmental and Socioeconomic Influences on Cognition11
- Genetics and Cognitive Abilities3
- IQ Scores and Ranges2
- Intelligence Research and Cognitive Abilities2
- Psychological Measurement and Testing27
- Psychometric Testing and IQ Assessment2
- Statistical Methods and Data Analysis23
- Statistical Methods in Psychology1
- Technological Advances in Psychology5
Latest articles
- Gifted Children: Identification and Testing
Most districts set the gifted cutoff at IQ 130, two standard deviations above the mean. What that threshold means, and which test suits which age.
- Executive Function in Children
Executive function is the umbrella term for the cognitive control processes that allow children to manage their attention, hold information in mind, resist impulses, and...
- Does Music Training Increase IQ?
The claim that music training raises intelligence is among the most durable in popular science. During the 1990s the “Mozart Effect” prompted widespread purchase of...
- Working Memory: Why It Matters
Working memory holds about four chunks, not seven. How capacity is measured, why it tracks fluid reasoning at r = 0.6, and whether training actually works.
- The G Factor: What General Intelligence Means
General intelligence accounts for 40 to 50 percent of variance in cognitive test performance and predicts job performance at r = 0.51. What the evidence shows.
- Sleep Deprivation and Cognitive Performance
Williamson and Feyer (2000), in Occupational and Environmental Medicine , ran a deceptively simple experiment: they kept healthy adults awake for 28 hours and tested...
- Mindfulness and Cognition: What Controlled Studies Show
Mindfulness improves attention and inhibition modestly, but the effect halves against active controls. What 111 randomized trials actually show.
- Traumatic Brain Injury and Cognition
Every year roughly 69 million people worldwide sustain a traumatic brain injury (TBI), and the question survivors and families ask first is rarely about scans or scores...
- Loneliness and Cognitive Decline: How Big Is the Risk?
The brain is, more than anything else, a social organ. Roughly 85 billion neurons evolved primarily to navigate other minds — to recognize faces, infer intentions,...
- Caffeine and Cognitive Performance
Caffeine is the world’s most widely consumed psychoactive substance — about 85 percent of American adults drink at least one caffeinated beverage daily, and global...